The broad, long-term objective of this proposal is to improve the prognosis of patients with coronary artery disease. We propose to use magnetic resonance imaging (MRI) to detect the presence of clinically significant coronary artery stenoses by assessing the myocardial T2 changes using a T2-weighted technique. The long term goal is to identify those patients at risk of ischemic heart disease who might benefit from vascular interventions such as percutaneous transluminal angioplasty or bypass graft. In the proposed project, a well-controlled animal model (dog) will be used. Various levels of coronary artery stenoses will be created. The studies will be performed on a state-of-the-art 3-Tesla imaging system to improve the sensitivity of the test. Compared to the conventional method of myocardial perfusion evaluation using first-pass contrast-enhanced technique, the proposed method has the advantage of potentially not requiring pharmacological stress test, and/or better spatial resolution and coverage. The specific aims of the proposed project are: Aim 1: To develop a T2-prepared three-dimensional true fast imaging with steady state precession technique for T2 measurement in the heart and to validate MR blood volume fraction measurement on phantom. Aim 2: To verify that regional myocardial T2 difference following direct adenosine injection into the coronary artery is greater at 3.0 T than that at 1.5 T. Aim 3: To test whether territory supplied by functionally significant coronary artery stenoses can be detected using T2-weighted MR imaging under resting conditions. Aim 4: To test whether MR T2-weighted imaging can detect a 2-fold regional difference in blood flow reserve under pharmacologic stress. Positive results from this project will warrant clinical studies in patients to evaluate the role of T2-weighted MR imaging in detecting functionally significant coronary artery disease.